uc3854bdw   

增強型高功率因子前置穩壓器

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產品信息

特性

• controls boost pwm to near-unity power factor
• limits line current distortion to <3%
• world-wide operation without switches
• accurate power limiting
• fixed-frequency average current-mode control
• high bandwidth (5 mhz), low-offset current amplifier
• integrated current- and voltage-amplifier output clamps
• multiplier improvements: linearity, 500 mv v_acoffset (eliminates external resistor), 0 v to 5 v multout common-mode range
• v_refgood comparator
• faster and improved accuracy enable comparator
• uvlo options (16 v/10 v or 10.5 v/10 v)
• 300-µa start-up supply current

說明

the uc3854a/b products are pin compatibleenhanced versions of the uc3854. like the uc3854, these products provide all of the functions necessary for active power factor corrected preregulators. the controller achieves near unity power factor by shaping the ac input line current waveform to correspond to the ac input line voltage. to do this the uc3854a/b uses average current mode control. average current mode control maintains stable, low distortion sinusoidal line current without the need for slope compensation, unlike peak current mode control.

a 1%, 7.5-v reference, fixed frequency oscillator, pwm, voltage amplifierwith soft-start, line voltage feedforward (v_rmssquarer), input supply voltage clamp, and over current comparator round out the lilst of feataures.